[PATCH] hugetlbfs: specify size & inodes at mount

From: "Seth, Rohit" <rohit.seth@intel.com>

- Add support for setting the filesystem's maximum size and maximum inode
  count on the mount command line.

  This is needed because the system admin can now set the ownership of teh
  fs to non-root users.  We don't want those users to be able to use all of
  the hugepage pool.

- Prroperly update the inode creation/modification time.

- Set the blocksize to HPAGE_SIZE (instead of PAGE_CACHE_SIZE).

- Update Documentation/vm/hugetlbpage.txt.

Documentation/vm/hugetlbpage.txt

@@ -68,14 +68,21 @@ call, then it is required that system administrator mount a file system of
 type hugetlbfs:
 
 	mount none /mnt/huge -t hugetlbfs <uid=value> <gid=value> <mode=value>
+		 <size=value> <nr_inodes=value>
 
 This command mounts a (pseudo) filesystem of type hugetlbfs on the directory
 /mnt/huge.  Any files created on /mnt/huge uses hugepages.  The uid and gid
 options sets the owner and group of the root of the file system.  By default
 the uid and gid of the current process are taken.  The mode option sets the
 mode of root of file system to value & 0777.  This value is given in octal.
-By default the value 0755 is picked.  An example is given at the end of this
-document.
+By default the value 0755 is picked. The size option sets the maximum value of
+memory (huge pages) allowed for that filesystem (/mnt/huge). The size is
+rounded down to HPAGE_SIZE.  The option nr_inode sets the maximum number of
+inodes that /mnt/huge can use.  If the size or nr_inode options are not
+provided on command line then no limits are set.  For size and nr_inodes
+options, you can use [G|g]/[M|m]/[K|k] to represent giga/mega/kilo. For 
+example, size=2K has the same meaning as size=2048. An example is given at 
+the end of this document. 
 
 read and write system calls are not supported on files that reside on hugetlb
 file systems.

include/linux/hugetlb.h

@@ -73,11 +73,28 @@ static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
 
 #ifdef CONFIG_HUGETLBFS
 struct hugetlbfs_config {
-        uid_t   uid;
-        gid_t   gid;
-        umode_t mode;
+	uid_t   uid;
+	gid_t   gid;
+	umode_t mode;
+	long	nr_blocks;
+	long	nr_inodes;
 };
 
+struct hugetlbfs_sb_info {
+	long	max_blocks;   /* blocks allowed */
+	long	free_blocks;  /* blocks free */
+	long	max_inodes;   /* inodes allowed */
+	long	free_inodes;  /* inodes free */
+	spinlock_t	stat_lock;
+};
+
+static inline struct hugetlbfs_sb_info *HUGETLBFS_SB(struct super_block *sb)
+{
+	return sb->s_fs_info;
+}
+
+#define PSEUDO_DIRENT_SIZE	20
+
 extern struct file_operations hugetlbfs_file_operations;
 extern struct vm_operations_struct hugetlb_vm_ops;
 struct file *hugetlb_zero_setup(size_t);